|Publication number||US7173411 B1|
|Application number||US 10/955,070|
|Publication date||Feb 6, 2007|
|Filing date||Sep 30, 2004|
|Priority date||Sep 30, 2004|
|Publication number||10955070, 955070, US 7173411 B1, US 7173411B1, US-B1-7173411, US7173411 B1, US7173411B1|
|Inventors||Robert J Pond|
|Original Assignee||Rockwell Automation Technologies, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (38), Classifications (10), Legal Events (3)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates generally to industrial control systems, and more particularly to systems and methodologies that facilitate reduction of current consumption in industrial control devices and temperature compensation, such as proximity sensors.
Industrial control systems have enabled modern factories to become partially or completely automated in many circumstances. These systems generally include a plurality of Input and Output (I/O) modules that interface at a device level to switches, contactors, relays and solenoids along with analog control to provide more complex functions such as Proportional, Integral and Derivative (PID) control. Communications have also been integrated within the systems, whereby many industrial controllers can communicate via network technologies such as Ethernet, Control Net, Device Net or other network protocols and also communicate to higher level computing systems. Generally, industrial controllers utilize the aforementioned technologies along with other technology to control, cooperate and communicate across multiple and diverse applications.
Conventional control systems employ a large array of varied technologies and/or devices to achieve automation of an industrial environment, such as a factory floor or a fabrication shop. Systems employed in an automated environment can utilize a plurality of sensors and feedback loops to direct a product through, for example, an automated assembly line. Such sensors can include temperature sensors (e.g., for determining a temperature of a steel bar that is entering a roller device to press the bar into a sheet . . . ), pressure sensors (e.g., for determining when a purge valve should be opened, for monitoring pressure in a hydraulic line . . . ), proximity sensors (e.g., for determining when an article of manufacture is present at a specific device and/or point of manufacture . . . ), etc.
Proximity sensors are available in a wide variety of configurations to meet a particular user's specific sensing needs. For example, sensors can be end-mounted in a housing, side-mounted in a housing, etc., to facilitate mounting in confined spaces while permitting the sensor to be directed toward a sensing region as deemed necessary by a designer. Additionally, proximity sensors are available with varied sensing ranges, and can be shielded or unshielded. Shielded inductive proximity sensors can be mounted flush with a surface and do not interfere with other inductive proximity sensors, but have diminished sensing range when compared with unshielded proximity sensors.
Of paramount importance in the field of proximity sensors is sensing distance, and, more specifically, increasing sensing distance. A problem often encountered when attempting to extend a sensing range of a proximity sensor is temperature drift, which can cause an error since the resistance change due to a target cannot be distinguished from a change due to temperature. Therefore, it is important to be able to determine coil temperature accurately. For example, an uncompensated change of 1° C. can create an error of about 0.4% in the measurement of the coil resistance. For an extended range 18 mm diameter unshielded sensors with a sensing range of 20 mm, the change in the effective resistance of the coil due to the presence of a target is about 1%. Thus it is seen that a small change in coil temperature can limit the accuracy of the proximity sensor.
As industrial control systems become more complex and as system demands require finer-tuned sensing devices, so too does proximity sensor efficiency become ever more important. Thus, a need exists in the art for systems and methods that facilitate increasing efficiency of sensing devices and accounting for temperature effects on sensing coils in proximity sensors in an industrial automation environment.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is not intended to identify key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The subject invention provides for systems and methods that facilitate increased accuracy in proximity sensors via determining a time constant value associated with a damping resonant circuit in a proximity sensor. This determination mitigates temperature drift effects and facilitates accurately ascertaining when a target has been sensed despite temperature deviations in a sensing coil. More specifically, the present invention can ascertain coil temperature via determining a value, γ, associated with an L/R time constant for a sensing coil, where L is inductance and R is resistance, associated with the resonant circuit. Thus, the invention can account for an effect of temperature on coil inductance to more accurately detect coil temperature.
According to one aspect of the invention, a “gamma” value associated with the L/R decay time constant of a sensing coil resonant circuit can be ascertained to help facilitate a determination of coil temperature. For example, an RC time constant can be assessed for the resonant circuit in order to facilitate determining an appropriate duration for a current pulse through the circuit, which in turn permits a determination of the L/R time constant value. According to this example, a first transistor device can be activated to provide current to the circuit for a period of approximately one RC time constant, which allows the capacitor in the circuit to charge to approximately 62.3% of full charge. It is to be appreciated, however, that other pulse durations are contemplated by the subject invention (e.g., two time constants, three time constants . . . ). The single time constant worth of current provides sufficient charge on the capacitor to permit a ringing oscillation to occur in the resonant circuit upon cessation of the current pulse. In this manner, the subject invention can facilitate a determination of coil temperature, and thus sensing distance variation, more quickly and accurately than conventional systems, which typically require many time constants to permit coil resistance to settle to a DC value prior to extrapolation of temperature information. Such conventional circuits are complex and require filters to separate DC and AC energy.
Upon cessation of the current pulse (e.g., deactivation of the first transistor device), a voltage can be measured for the capacitor, and thereafter a second transistor device can be activated. During this period, a charge stored in the capacitor will decay as it rings through an inductor in the resonant circuit. A second voltage measurement can be obtained during an oscillatory decay of the stored charge, which measured value can be divided by the first measured voltage value to determine a value, γ, related to an L/R time constant for the circuit. The gamma damping factor accounts for both resistive and inductive temperature effects on the coil to permit an accurate determination of coil temperature. For example, in an extended range proximity sensor, changes in coil resistance due to the introduction of a target in to a sensing field are typically negligible at extended ranges due to the relatively large distance of the target. Thus, coil resistance is predominantly a function of coil temperature and the natural resistivity of the coil. However, coil inductance is affected by the introduction of a target into the sensing field, even at extended ranges.
To the accomplishment of the foregoing and related ends, certain illustrative aspects of the invention are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention can be employed and the present invention is intended to include all such aspects and their equivalents. Other advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.
The present invention will now be described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. The present invention will be described with reference to systems and methods for determining coil temperature in a proximity sensor via measuring a time constant of the coil. It should be understood that the description of these exemplary aspects are merely illustrative and that they should not be taken in a limiting sense.
The term “component” can refer to a computer-related entity, either hardware, a combination of hardware and software, software, or software in execution. For example, a component can be a process running on a processor, a processor, an object, an executable, a thread of execution, a program and a computer. By way of illustration, both an application running on a server and the server can be components. A component can reside in one physical location (e.g., in one computer) and/or can be distributed between two or more cooperating locations (e.g., parallel processing computer, computer network).
It is to be appreciated that various aspects of the present invention can employ technologies associated with facilitating unconstrained optimization and/or minimization of error costs. Thus, non-linear training systems/methodologies (e.g., back propagation, Bayesian, fuzzy sets, non-linear regression, or other neural networking paradigms including mixture of experts, cerebella model arithmetic computer (CMACS), radial basis functions, directed search networks, custom integrated circuits and function link networks) can be employed.
Given the importance of temperature with respect to coil sensing capabilities, many attempts at compensation have been introduced, including: adding a temperature sensing or compensating element, which often does not track the coil temperature due to temperature gradients within the sensor, and tolerances associated with the compensating element also introduce errors; special coil and/or oscillator construction or multiple coil assemblies, which add cost since they are more complex than a simple two-terminal sensing coil and require special handling of the tiny Litz wire coil windings; adding a reference coil and/or oscillator, which often is not at the same temperature as the sensing coil due to temperature gradients and increased circuit complexity; non-resonant circuit L/R time constant methods, which require more current since the circuit is not resonant and the transient L/R value may be representative of the value at the sensor operating frequency; DC coil resistance measurement, which requires a highly complex circuit and high power to attain usable signal levels since the coil resistance is often low; etc. The subject invention provides improved temperature compensation and sensor operation over such conventional compensation schemes.
The system 100 comprises a control component 102 that can receive and analyze information from a measuring component 104 to determine a damping factor associated with a time constant (e.g., a quotient derived from the inductance, L, of the sensor coil, and the resistance, R, thereof). The measuring component 104 can monitor a proximity sensor 106, and more specifically, a resonant damping circuit in the proximity sensor 106 to facilitate a determination of coil temperature as a product of a damping factor for a resonant circuit in the sensor 106.
For example, a resonant circuit can comprise resistors, capacitors, inductors, etc., that can be manipulated via selective energization of one or more voltage sources in the circuit. One or more gates or transistors (e.g., MOSFETS, . . . ) can additionally be employed to permit selective manipulation of the circuit in order to facilitate obtaining measurements related to circuit parameters at various times during circuit operation and/or monitoring. According to this example, the control component can charge the capacitor C1 through a resistance R1 for a fixed time interval. This time interval can be determined to be approximately one R1C1, time constant based upon design parameters. The voltage established on the capacitor C1 is a function of the supply voltage and the R1C1 time constant. If the time interval and precision resistor R1 are fixed, then any changes in the voltage on the capacitor C1 are due to changes in C1. The charging period is activated by closing a first transistor via the control component 102.
Once the current pulse has been terminated by the control component 102, the measuring component 104 can perform a first voltage measurement V1. The control component 102 can then apply a second voltage source to the resonant circuit via a second transistor in the proximity sensor 106, and, after a predetermined temporal period Δt, a second voltage measurement V2 can be taken by the measuring component 104. The second voltage measurement can provide information related to the voltage characteristics of an inductor L1 in series with a second resistor R2 in the resonant circuit. A value, γ, which includes expressions related to temperature effects associated with both resistance and inductance, can be determined via dividing the second measured voltage by the first measured voltage. The quotient, γ, of the voltages can be represented as:
By determining the gamma value, which is related to the time constant τL/R (e.g., where τL/R=L1/2R2) of the resonant circuit, the system 100 can account for inductive as well as resistive aspects of temperature effects on the sensing coil in the proximity sensor 106. Once known, γ can be employed to determine coil temperature. The derivation of γ and various voltage measurement calculations is described in greater detain infra, with respect to
The control component 102 can then direct the proximity sensor 106 to obtain a measurement of a distance to a target. Depending on temperature variances from a predetermined reference temperature, T0, the sensor 106 can read an incorrect distance to the target. The sensed distance can be described as a function of temperature wherein:
T s =T s(s,T)=2π(L 1 C 1)1/2
where L1=L1(s,T), C1=C1(T), and R2=R2(s,T), and where s is distance, T is temperature, and Ts is the measured period, or the reciprocal of a frequency of the resonant circuit. The natural logarithm of the γ value can be taken to yield the expression lnγ=−R2Δt/2L1, which can be utilized to determine the exact temperature of the coil. Solving for the inductance:
L 1=(T s 2)/(4π2 C 1)=L S +L T
At this point, since the measured gamma or the natural log of gamma can be used to determine coil temperature, a correction value to the measured inductance found from Ts can be deduced. For example, a lookup can be performed to determine a portion of inductance due to temperature LT, which can be predetermined, known from experimentation, design processes, etc. The difference between L1 and LT is LS, the portion of inductance in the coil that is due to a target. LS can then be compared to a reference value to determine whether the sensor has been tripped, etc., such that if the measured LS is greater than or equal to the reference value, then the sensor has been tripped. Thus, via employing both resistance and inductance in a single value determined from measured oscillatory decay characteristics of a damped resonant circuit in a proximity sensor, the present invention can determine sensor coil temperature in a highly accurate manner.
Additionally and/or alternatively, coil temperature can be determined via manipulating the gamma value as follows:
d(lnγ)=−(Δt/2L 1)(∂R 2 /∂T)dT−(Δt/2L 1)(∂R 2 /∂s)ds+(Δt/2L 1 2)(∂L 1 /∂T)dT+(Δt/2L 1 2)(∂L 1 /∂s)ds
However, the change in the coil resistance R2 is typically small with respect to s (e.g., toward the sensing limit, or trip point, . . . ) in extended range proximity sensors. Similarly, the change in L1 with respect to s and T is also typically very small compared to the change in resistance with temperature. Thus, the last three terms in the above expression are generally of such small values as to be negligible, and the expression can be simplified to:
d(lnγ)=−(Δt/2L 1)(∂R 2 /∂T)dT
where solving for dT yields:
Thus, dT, the change in temperature (e.g., from factory calibrated reference temperature value) can be determined from the natural log of the γ value. Resistance and inductance variations with respect to temperature can be predetermined and/or known from experimentation, design processes, etc.
It is to be appreciated that taking the natural log of the gamma value facilitates the determination of the change in temperature of the sensor coil, but is not necessarily essential to all aspects of temperature determination, as other manipulations of the gamma value and/or components thereof can be performed in accordance with aspects of the subject invention.
For example, temperature can be measured in the sensor coil via conventional means (e.g., sensors, . . . ) and a lookup can be performed to determine a portion of inductance due to temperature LT, which can be predetermined, known from experimentation, design processes, etc. The difference between L1 (e.g., as derived from the gamma value) and LT is LS, the portion of inductance in the coil that is due to a target. LS can then be compared to a reference value to determine whether the sensor has been tripped, etc., such that if the measured LS is greater than or equal to the reference value, then the sensor has been tripped.
It is to be understood that the processor 208 can be a processor dedicated to analyzing information associated with the sensor 206, increasing sensing distance and/or reducing sensor current consumption, a processor used to control one or more of the components of the system 200, or, alternatively, a processor that is both used to analyze information, increase sensing distance and/or reduce sensor current consumption, and to control one or more of the components of the system 200. The memory component 210 can be employed to retain information associated with coil temperature, time constant(s), inductance, sensing distance, and/or any other information related to the system 200.
Furthermore, the memory 210 can be either volatile memory or nonvolatile memory, or can include both volatile and nonvolatile memory. By way of illustration, and not limitation, nonvolatile memory can include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable ROM (EEPROM), or flash memory. Volatile memory can include random access memory (RAM), which acts as external cache memory. By way of illustration and not limitation, RAM is available in many forms such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM). The memory 210 of the present systems and methods is intended to comprise, without being limited to, these and any other suitable types of memory.
Still referring to
For example, the AI component 312 can infer an appropriate duration of a current pulse through a resonant circuit in the proximity senor 306 in order to facilitate a determination of a time constant for a sensing coil therein, which in turn can permit a highly accurate determination of coil temperature. The coil temperature can then be employed to determine sensing distance as a function of temperature variation on inductance in the sensing coil. Additionally, the particular resonant circuit employed in the proximity sensor 306, in combination with the methods described herein for determining coil temperature, permit such determinations to be made with far less current consumption than conventional systems and/or methodologies.
According to another example, the AI component 312 can make inferences regarding coil temperature in the proximity sensor 306, based at least in part on voltage measurements taken by the measuring component 304 during a test phase. Such inferences can be employed to predict sensing distance variation as a function of the effects of temperature variation on inductance, as well as resistance, in the sensing coil of the proximity sensor 306.
For example, when an object enters the electromagnetic field 504 of the proximity sensor 500, eddy currents are induced in the object as a result of the influence of the electromagnetic field 504. Losses created thereby can effectively be reflected back to the sensing coil 502 and increase the resistance, decrease the inductance, etc. thereof. By determining a time constant based on the inductance and resistance of particular components in a resonant circuit in the proximity sensor, the subject invention can determine a temperature of the coil 502 and assess its impact on sensing distance using substantially les current than conventional systems and/or methodologies while mitigating the duration of a testing period in which the effects of temperature variance are assess. This in turn improves the duty cycle of proximity sensor with respect to typical assessment methods that require longer testing periods.
Additionally, the resonant damping portion of the circuit 700 comprises an inductor L1 and a second resistor R2. Exemplary standard values for L1 and R2 can be, for instance, 324 μH and 2.73Ω (e.g., a typical resistance for copper wire in a sensing coil at a standard reference temperature), respectively, although the components are not limited to such values, but rather can comprise any suitable values to provide functionality to the subject invention. Additionally, it is to be understood that the inductance and resistance values described above can vary as temperature changes, for which variances the subject invention accounts.
During the initial charging pulse, the left side of C1 is essentially grounded because L1 is a low impedance, and thus the charge on C1 is determined by the duration of a voltage applied to VP. The longer a voltage is applied to VP, the higher the charge on C1; therefore, the duration of the voltage application to VP to provide the current pulse can be limited to a approximately one τRC to limit current consumption by the sensor during a test sequence. The capacitor C1 can be charged via application of a voltage described by the following expression:
Upon cessation of the current pulse (e.g., M1 is turned off, or opened) the voltage on VCAP can be measured and the measurement designated as V1 (illustrated in
V 1 =V P e −(R
V1 can be measured to determine a peak value therefore, which results in the argument of the sine being equal to 1, thereby simplifying the above equation to:
V 1 =V P e −(R
After the voltage VP has been measured, M2 can be closed, forming a damped oscillatory RLC circuit where energy is supplied by the voltage on C1. During the decay the zero crossings of the resonant circuit voltage, VAD, can be used to determine the sensor frequency change using techniques that are well known in the art. This can be determined, for example, from measurements at S3 and S4 (
After a decay time, t2, where t2 is chosen so that ωt2=ωt1+2nπ, (n is an integer), VAD can be measured to determine a peak value V2 there for, such that:
V 2 =V P e −(R
Again, the measurement can be taken to determine a peak voltage in order to ensure that the sine of the argument ωt2 is equal to 1, which permits reduction of the expression immediately above to:
V 2 =V P e −(R
The expressions for V1 and V2 can be manipulated to produce a value, γ, which is independent of voltage amplitude.
γ=(V 2 /V 1)=e −(R
where Δt represents the change in time between t0 and t2. From the γ value, coil temperature can be determined. Resistance is a linear function of temperature, which relationship is based on a temperature coefficient (e.g., the temperature coefficient for copper is approximately 0.004/C). When employing the subject systems and methodologies to determine coil temperature in an extended range proximity sensor, changes in resistance due to a target are largely negligible because the target is sufficiently distant when detected. Thus, coil resistance in extended range proximity sensors is mainly dependent on the coefficient of resistance for the coil material and the temperature of the coil. However, the target does have an effect on coil inductance which can be determined by measuring the frequency (or period) of the free decay oscillation.
Now turning to
The fundamental component of the square wave current excites the narrow band resonant tank circuit so that the tank voltage is sinusoidal as shown in
With reference to
γ=(V 6 /V 2)=e −(R
Turning briefly to
At 1212, gamma value associated with an L/R time constant for the sensing coil in the oscillatory resonant damping circuit that is independent of voltage amplitude can be determined via manipulation of the peak voltage measurements. For example, dividing the second measured peak voltage by the first measured voltage provides a value that is independent of voltage amplitudes and representative of the L/R time constant for the circuit, thus accounting for temperature effects associated with inductance in the sensing coil. At 1214, coil temperature can be determined via manipulation of the gamma value, as described herein. This method of temperature compensation automatically includes the L/R ratio, thereby mitigating a need for comparing resonant impedance with a reference resistor. Due to this aspect of the subject invention, current consumption is reduced because the current pulse duration is kept short (e.g., the circuit need not settle to a DC value prior to measurement, which typically requires a minimum pulse duration of 4–5 time constants, . . . ), thereby reducing down time of the sensor during accuracy testing and/or temperature assessment.
In order to provide a context for the various aspects of the invention,
It will be appreciated that the invention can also be implemented by custom integrated circuits which perform the control and measurement function. For example, the measured voltages need not be digital values resulting from A/D conversions, but can be treated in the analog realm, as in a sample and hold circuit, accompanied by operational amplifiers and/or comparator circuits to perform the control and measurement functions, or any other suitable analog arrangement.
With reference to
The system bus 1418 can be any of several types of bus structure(s) including the memory bus or memory controller, a peripheral bus or external bus, and/or a local bus using any variety of available bus architectures including, but not limited to, 8-bit bus, Industrial Standard Architecture (ISA), Micro-Channel Architecture (MSA), Extended ISA (EISA), Intelligent Drive Electronics (IDE), VESA Local Bus (VLB), Peripheral Component Interconnect (PCI), Universal Serial Bus (USB), Advanced Graphics Port (AGP), Personal Computer Memory Card International Association bus (PCMCIA), and Small Computer Systems Interface (SCSI).
The system memory 1416 includes volatile memory 1420 and nonvolatile memory 1422. The basic input/output system (BIOS), containing the basic routines to transfer information between elements within the computer 1412, such as during start-up, is stored in nonvolatile memory 1422. By way of illustration, and not limitation, nonvolatile memory 1422 can include read only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable ROM (EEPROM), or flash memory. Volatile memory 1420 includes random access memory (RAM), which acts as external cache memory. By way of illustration and not limitation, RAM is available in many forms such as synchronous RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct Rambus RAM (DRRAM). Computer 1412 also includes removable/non-removable, volatile/non-volatile computer storage media.
It is to be appreciated that
A user enters commands or information into the computer 1412 through input device(s) 1436. Input devices 1436 include, but are not limited to, a pointing device such as a mouse, trackball, stylus, touch pad, keyboard, microphone, joystick, game pad, satellite dish, scanner, TV tuner card, digital camera, digital video camera, web camera, and the like. These and other input devices connect to the processing unit 1414 through the system bus 1418 via interface port(s) 1438. Interface port(s) 1438 include, for example, a serial port, a parallel port, a game port, and a universal serial bus (USB). Output device(s) 1440 use some of the same type of ports as input device(s) 1436. Thus, for example, a USB port may be used to provide input to computer 1412, and to output information from computer 1412 to an output device 1440. Output adapter 1442 is provided to illustrate that there are some output devices 1440 like monitors, speakers, and printers, among other output devices 1440, which require special adapters. The output adapters 1442 include, by way of illustration and not limitation, video and sound cards that provide a means of connection between the output device 1440 and the system bus 1418. It should be noted that other devices and/or systems of devices provide both input and output capabilities such as remote computer(s) 1444.
Computer 1412 can operate in a networked environment using logical connections to one or more remote computers, such as remote computer(s) 1444. The remote computer(s) 1444 can be a personal computer, a server, a router, a network PC, a workstation, a microprocessor based appliance, a peer device or other common network node and the like, and typically includes many or all of the elements described relative to computer 1412. For purposes of brevity, only a memory storage device 1446 is illustrated with remote computer(s) 1444. Remote computer(s) 1444 is logically connected to computer 1412 through a network interface 1448 and then physically connected via communication connection 1450. Network interface 1448 encompasses communication networks such as local-area networks (LAN) and wide-area networks (WAN). LAN technologies include Fiber Distributed Data Interface (FDDI), Copper Distributed Data Interface (CDDI), Ethernet/IEEE 1102.3, Token Ring/IEEE 1102.5 and the like. WAN technologies include, but are not limited to, point-to-point links, circuit switching networks like Integrated Services Digital Networks (ISDN) and variations thereon, packet switching networks, and Digital Subscriber Lines (DSL).
Communication connection(s) 1450 refers to the hardware/software employed to connect the network interface 1448 to the bus 1418. While communication connection 1450 is shown for illustrative clarity inside computer 1412, it can also be external to computer 1412. The hardware/software necessary for connection to the network interface 1448 includes, for exemplary purposes only, internal and external technologies such as, modems including regular telephone grade modems, cable modems and DSL modems, ISDN adapters, and Ethernet cards.
What has been described above includes examples of the subject invention. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the subject invention, but one of ordinary skill in the art may recognize that many further combinations and permutations of the subject invention are possible. Accordingly, the subject invention is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4378504 *||Apr 2, 1982||Mar 29, 1983||Omron Tateisi Electronics Co.||Proximity switch|
|US4543527 *||Apr 12, 1982||Sep 24, 1985||Eaton Corporation||Proximity switch exhibiting improved start-up characteristics|
|US5278523 *||Jan 11, 1990||Jan 11, 1994||Christian Lohse Beruhrungslose Schalttechnik||Temperature-stable tuned-circuit oscillator, especially in a proximity switch|
|US5508662 *||Apr 4, 1995||Apr 16, 1996||Schneider Electric Sa||Variable frequency inductive proximity sensor|
|US6191580 *||Nov 30, 1998||Feb 20, 2001||Schneider Electric Sa||Configurable inductive proximity detector to detect ferrous or non-ferrous metal objects|
|US6529007 *||Dec 1, 2000||Mar 4, 2003||Ellen Ott||Temperature compensation for ground piercing metal detector|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7674994 *||Oct 21, 2005||Mar 9, 2010||Valerio Thomas A||Method and apparatus for sorting metal|
|US7924105||Mar 5, 2009||Apr 12, 2011||Pepperl + Fuchs Gmbh||Method for the detection of a predamping state and inductive sensor with predamping detection|
|US8008909 *||Dec 22, 2006||Aug 30, 2011||Knorr-Bremse Systeme Fuer Nutzfahrzeuge Gmbh||Analysis and compensation circuit for an inductive displacement sensor|
|US8138437||Aug 27, 2010||Mar 20, 2012||Thomas A. Valerio||Method and system for recovering metal from processed recycled materials|
|US8154278 *||Nov 14, 2008||Apr 10, 2012||Pepperl+Fuchs, Inc.||Metal face inductive proximity sensor|
|US8158902||Apr 17, 2012||Thomas A. Valerio||Method and apparatus for sorting metal|
|US8159234 *||Aug 10, 2009||Apr 17, 2012||Panasonic Corporation||Proximity sensor|
|US8177069||May 15, 2012||Thomas A. Valerio||System and method for sorting dissimilar materials|
|US8201692||Jun 19, 2012||Thomas A Valerio||Materials separation module|
|US8360242 *||Nov 16, 2009||Jan 29, 2013||Thomas A. Valerio||Wire recovery system|
|US8360347||Jan 29, 2013||Thomas A. Valerio||Method and system for separating and recovering wire and other metal from processed recycled materials|
|US8378660 *||Feb 19, 2013||Microchip Technology Incorporated||Programmable integrated circuit device to support inductive sensing|
|US8523429 *||Oct 14, 2010||Sep 3, 2013||Tsi Technologies Llc||Eddy current thermometer|
|US8627960||Apr 28, 2010||Jan 14, 2014||Mtd America Ltd (Llc)||Apparatus and method for separating materials using air|
|US8757523||Nov 1, 2010||Jun 24, 2014||Thomas Valerio||Method and system for separating and recovering wire and other metal from processed recycled materials|
|US20070187299 *||Oct 24, 2006||Aug 16, 2007||Valerio Thomas A||Dissimilar materials sorting process, system and apparata|
|US20080257793 *||Jan 7, 2008||Oct 23, 2008||Valerio Thomas A||System and method for sorting dissimilar materials|
|US20080257794 *||Apr 18, 2008||Oct 23, 2008||Valerio Thomas A||Method and system for sorting and processing recycled materials|
|US20090189600 *||Nov 14, 2008||Jul 30, 2009||Pepperl+Fuchs, Inc.||Metal face inductive proximity sensor|
|US20090224841 *||Mar 5, 2009||Sep 10, 2009||Thomas Kuehn||Method for the detection of a predamping state and inductive sensor with predamping detection|
|US20090302868 *||Dec 22, 2006||Dec 10, 2009||Thomas Feucht||Analysis and Compensation Circuit for an Inductive Displacement Sensor|
|US20100013116 *||Jul 21, 2009||Jan 21, 2010||Blyth Peter C||Method and System for Removing Polychlorinated Biphenyls from Plastics|
|US20100033197 *||Feb 11, 2010||Masahisa Niwa||Proximity sensor|
|US20100051514 *||Nov 16, 2009||Mar 4, 2010||Mtd America, Ltd.||Materials Separation Module|
|US20100090717 *||Sep 16, 2009||Apr 15, 2010||Microchip Technology Incorporated||Programmable Integrated Circuit Device to Support Inductive Sensing|
|US20100126913 *||Nov 16, 2009||May 27, 2010||Mtd America, Ltd.||Wire Recovery System|
|US20100126914 *||Nov 16, 2009||May 27, 2010||Mtd America, Ltd.||Plastic Separation Module|
|US20100168907 *||Dec 29, 2009||Jul 1, 2010||Valerio Thomas A||Method and apparatus for sorting contaminated glass|
|US20100224537 *||Mar 9, 2010||Sep 9, 2010||Valerio Thomas A||Method and Apparatus for Sorting Metal|
|US20110017644 *||Jul 21, 2010||Jan 27, 2011||Valerio Thomas A||Method and System for Separating and Recovering Like-Type Materials from an Electronic Waste System|
|US20110024531 *||Feb 3, 2011||Valerio Thomas A||Method and System for Separating and Recovering Wire and Other Metal from Processed Recycled Materials|
|US20110067569 *||Apr 28, 2010||Mar 24, 2011||Mtd America Ltd (Llc)||Apparatus and Method for Separating Materials Using Air|
|US20110090937 *||Oct 14, 2010||Apr 21, 2011||Tsi Technologies Llc||Eddy current thermometer|
|US20110147501 *||Nov 1, 2010||Jun 23, 2011||Valerio Thomas A||Method and System for Separating and Recovering Wire and Other Metal from Processed Recycled Materials|
|US20130015177 *||Jul 12, 2012||Jan 17, 2013||Tsi Technologies Llc||Induction heating system employing induction-heated switched-circuit vessels|
|US20130315281 *||Aug 6, 2013||Nov 28, 2013||Tsi Technologies Llc||Eddy current thermometer|
|US20140002069 *||Jun 27, 2012||Jan 2, 2014||Kenneth Stoddard||Eddy current probe|
|EP2099134A1||Mar 6, 2008||Sep 9, 2009||Pepperl + Fuchs Gmbh||Method for recognising a pre-vapour deposition state and inductive sensor with pre-vapour deposition recognition|
|U.S. Classification||324/207.12, 324/225, 324/207.15, 324/207.26|
|International Classification||G01B7/00, G01R33/025|
|Cooperative Classification||H03K17/9502, H03K17/9547|
|European Classification||H03K17/95B, H03K17/95H8D4|
|Sep 30, 2004||AS||Assignment|
Owner name: ROCKWELL AUTOMATION TECHNOLOGIES, INC., OHIO
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:POND, ROBERT J.;REEL/FRAME:015864/0505
Effective date: 20040930
|Aug 6, 2010||FPAY||Fee payment|
Year of fee payment: 4
|Aug 6, 2014||FPAY||Fee payment|
Year of fee payment: 8